Huge plumes of smoke drifted across the skies of the Canary Islands yesterday as two big forest fires forced 10,000 people out of their homes to seek safety away from the spreading flames.

Strong winds and soaring temperatures helped the fires spread rapidly through inland areas of both Gran Canaria and Tenerife as authorities admitted they were struggling to contain them.

Some 24,000 hectares (60,000 acres) of land had gone up in smoke by yesterday morning. Authorities said that a fire that had been raging for four days on the island of Gran Canaria would have devoured up to 20,000 hectares by the end of the day. The fire, in a high-lying area to the south of the island, led to 5,200 people being evacuated from the municipality of Mogán and neighbouring areas.

A local forest warden has been arrested on suspicion of starting the fire in protest at being told that he would be laid off from his job in September.

Temporary warden Juan Antonio Navarro was remanded in custody after police blamed him for a fire which he had been the first to report.

"This is one of the worst, if not the worst ever, fires on the island," said the special prosecutor for environmental crimes, Guillermo García Panasco.

Eleven firefighting helicopters and planes were at work dropping water on the steep slopes of Gran Canaria as hill-top military and civilian communications centres came under threat.

A further five aircraft were fighting a fire on the island of Tenerife that had burned up to 14,000 hectares of land since it started on Monday, authorities said.

More than 4,000 people had been evacuated from municipalities to the west of the soaring Teide volcano as this fire, too, was pushed by strong winds.

With winds reaching up to 43 mph on Gran Canaria, no one was prepared to predict when the fire might eventually be put out.

"The landscape of the islands makes it very difficult to fight the fires except for from the air - though the high temperatures and wind are making things difficult," said Paulino Rivero, president of the regional government.

Hundreds of soldiers have been called in to help firefighting crews on both islands. Two soldiers were injured yesterday when their tanker truck overturned.

None of the big tourism centres on the islands were under threat yesterday. But the fire has damaged 65% of the Palmitos bird sanctuary park. There are fears that exotic birds may have been killed.

Some 5 million tourists visit the Canary Islands, which lie off the coast of west Africa, every year.

A relatively mild summer across most of mainland Spain so far has meant these are the country's first big fires of the year. Last year 80,000 hectares were burned in Galicia, on the north-western mainland.

Eleven firefighters died in 2005 when they were cut off by flames in a fire near Guadalajara, central Spain.